Extending cables down through wellbores, is a very common exercise, especially in hydrocarbon production/injection and exploration operations. Cable protecting devices in various forms are also known for rigidly holding the cable, to transfer its weight to the well bore conduit or tubing during operation. Such devices also serve to prevent the cable from moving within the well bore, so that it does not undergo abrasion or wearing by impact or rubbing with the well wall or casing. Such movement may take place for example, when a motor of a submerged electric pump, to which the cable is connected, is put on or put off, which trigger vibrations within the well bore. Such movement may also take place during lifting/lowering of any equipment with the cable attached.
Now, the cable protecting devices known in the art are usually mounted on pipes, such as but not limited to production tubing. The cables may be banded or strapped to the production tubing at intervals, for transferring the weight of the cable on the production tubing.
In the prior art known in the field, various cable protecting devices have been taught and disclosed, however there has not been much focus on mounting or installing the cable protecting device conveniently on the connections in the down hole pipes, in a simple, less time consuming and rigid manner. One example (for example publication no. WO 2006/073309) discloses a cable retaining strip having a longitudinally extending cable track for holding the cable. The strip is provided with two attaching members. The cable track and the attaching members have holes for welding the strip to an underlying pipe. A problem related to the protection of the cable is related to connections or pipe joints along the pipe, where a sleeve having a wider diameter than the pipe and the cable has to pass the sleeve or collar. Several cable clamps have been suggested for this use, eg. as shown in WO94/0011609, GB2398807, GB2274294 and US2009/078020 where all of them require fastening means extending around the pipe.
The above prior art document and also other documents do not focus on the fact that mounting the cable protection devices on pipes is time consuming. This is particularly true, because fairly a large number of such devices, are required in each well. Additionally the current devices require more than one person present close to the pipe to install onto, introducing danger of personnel injury in the process.
Additionally, the cable protecting devices or its parts as known in the art, which are known to be mounted on such pipes, for example production tubings, have potential chances of falling off inside the well, which obviously requires substantially expensive, recovery and corrective operations.
Thus it is an object of this invention to provide a cable protecting device for protecting cables which has a simple arrangement for rigidly mounting it on a pipe joint, especially on a connection in a down hole pipe, so that the mounting and removal operation of the device is not time consuming and simultaneously being sufficiently secure to reduce the chances of falling off of the device or its parts into the well bore. The object of the invention is obtained with a device according to the accompanying claims.
Thus the present invention provides a cable protecting device for protecting cables, which extends over a collar or sleeve on a pipeline. The collar extends around the circumference of the pipeline for a known length and has a first and second end surface. The cable protecting device or clamp according to the invention is longer than the collar, and occupies a sector of the space between the pipe and the casing or borehole outside. The inner surface is preferably curved, with a radius to generally fit smugly on the outside of the pipeline and collar. The inner radius at the ends of the device is therefore smaller than that of the middle part, preferably just slightly larger than that of the pipeline, thus defining a recess in the clamp for enclosing the outer surface and ends of the collar.
According to the invention, the length of the second recess corresponds essentially to the length of the collar and each end of the second recess is provided with engaging means for engaging into the corresponding end surface of the collar. Hence, the cable protecting device is fixed to the collar of the pipeline in a rigid manner, which is substantially less time consuming.
According to a preferred embodiment of the cable protecting device of the present invention at least one of the engaging means is spring loaded so as to apply a force through the engaging means into the corresponding end of the collar.
Preferably, the engaging end of the engaging means is wedge shaped.
More preferably the spring is provided with a release mechanism for allowing the engaging means to engage or disengage into or from said collar end.
Most preferably, the spring loaded is a spring fastened to the protecting device through a fastening means, having a high thermal expansion extending inside one end of the spring, so as to increase the grip on the spring in high temperature environments.